#themeFab {
  width: 44px;
  height: 44px;
  display: grid;
  place-items: center;
}

.theme-fab-pop {
  animation: themeFabPop 220ms ease-out;
}

@keyframes themeFabPop {
  0%   { transform: scale(0.92); }
  55%  { transform: scale(1.10); }
  100% { transform: scale(1.00); }
}